What this says is "Show a window named EMP_WINDOW (creating it if you need to). It should contain just the EMPLOYEES business object. Set its opening information string to the value of #EMPNO".

Now imagine a filter (or command handler) that is either started, or already active, inside the window EMP_WINDOW.

It has this special 'Wake up' method in it:

Mthroutine uShowWindowCompleted Options(*Redefine)

#Empno := #Com_Owner.avCurrentWindow.OpenInfo<1>

Use message_box_show (ok ok info *Component #Empno)

Endroutine

This method is invoked every time some other window executes:

#AvFrameworkManager.avShowWindow WindowName(EMP_WINDOW)

In other words, this is a method that is saying 'wake up, another window wants you to do something'. Typically the command handler or filter that is 'woken up' would use information passed in the open information strings to determine what it should do next.

This feature may be used to interlink high level business objects. For example imagine a window working with details named CUSTOMER_WINDOW and another working with order information named ORDER_WINDOW.

Scattered through the command handlers belonging to CUSTOMER_WINDOW you would find method calls like this: